> It has been VERY cold here in Northern Virginia for the past day or so.
> I don't know what the low was last night, but at 7AM it was 9 degrees out
> (all temperatures Fahrenheit) and I had heard the 30 to 40 mph winds howling
> around the house all night.
Scott, given that and the rest of your description, my guess is that there is
nothing really wrong except your antifreeze protection wasn't up to snuff.
> I notice on the ground that there is a long trail of green coolant running
> down the driveway from this morning's events.
> Is it my imagination, or does it look slushy?
I don't think it was your imagination ...
> I thought that even if you had a pretty poor mixture of antifreeze and water
> in your system that you were protected to well below zero degrees.
It depends on your definition of "protected". What happens is that it does
protect the engine from freezing hard enough to break something, but not from
forming slush in the cooling system that does not circulate well and causes
exactly the symptoms you experienced. The water pump cannot move the slush and
so there is no circulation. The water gets hot enough to boil, only around the
valves in the head and when it does boil, it forces slush & all out through the
overflow. Since only a small amount of water is actually that hot, the temp
gauge only 'sees' the boiling water for a second or two & so the slow responding
TR4 electrical gauge never shows you what's happening. (A TR3 mechanical gauge
will, if you happen to be watching it at the right second)
Put it to bed tonight with a blankie & a night light (100 watts will likely do,
if the blanket blocks all the wind), then tomorrow top it up with pure
antifreeze and try again. If it boils again, shut it off for a few minutes, top
it up & try again. I can recall having to repeat the process 5 or 6 times
(although it wasn't my TR that was frozen). Water is actually a very poor
conductor of heat, but the warmth will eventually spread enough to melt the